Projection of Heat Injury to Single-Cropping Rice in the Middle and Lower Reaches of the Yangtze River, China under Future Global Warming Scenarios

Based on simulation results from the 16 CMIP5 model runs under three Representative Concentration Pathways (RCP2.6, RCP4.5, and RCP8.5) in combination with the recent five years of growth-stage data from agrometeorological observation stations in the middle and lower reaches of the Yangtze River, changes in heat injury and spatial distribution patterns of single-cropping rice in China during the early (2016–35), middle (2046–65), and late (2080–99) 21st century were projected by using quantitative estimations. Relative to the reference period (1986–2005), the occurrence probabilities of heat injury to single-cropping rice under different RCP scenarios increased significantly, showing a trend of mild > moderate > severe. The occurrence probabilities increased with time and predicted emissions, especially the average and maximum occurrence probabilities, which were ~48% and ~80%, respectively, in the late 21st century under the RCP8.5 scenario. The spatial patterns of the occurrence probabilities at each level of heat injury to single-cropping rice did not change, remaining high in the middle planting region and low in the east. The high-value areas were mainly in central Anhui and southeastern Hubei provinces, and the areas extended to the northwest and northeast of the cultivation area over time. Under the RCP2.6, RCP4.5, and RCP8.5 scena-rios, the total area of heat injury to single-cropping rice showed a significant linear increasing trend of 7.4 × 10³, 19.9 × 10³, and 35.3 × 10³ ha yr^–1, respectively, from 2016 to 2099, and the areas of heat injury were greatest in the late 21st century, accounting for ~25%, ~40%, and ~59% of the cultivation area.